syzbot suspects this bug was fixed by commit:

commit 32c72165dbd0e246e69d16a3ad348a4851afd415 Author: Kadlecsik József kadlec@blackhole.kfki.hu Date: Sun Jan 19 21:06:49 2020 +0000

netfilter: ipset: use bitmap infrastructure completely

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13435a7ee00000 start commit: 8f8972a3 Merge tag 'mtd/fixes-for-5.5-rc7' of git://git.ke.. git tree: upstream kernel config: https://syzkaller.appspot.com/x/.config?x=d9290aeb7e6cf1c4 dashboard link: https://syzkaller.appspot.com/bug?extid=33fc3ad6fa11675e1a7e userspace arch: i386 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15982cc9e00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11be38d6e00000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: netfilter: ipset: use bitmap infrastructure completely

For information about bisection process see: https://goo.gl/tpsmEJ#bisection